Catalytic isomerization



March 11, 1947. w. R. sMzTH 2,417,221 CATALYTIC ISOMERIZATION Filed Jan. 11, 194

WILLIAM RSmTH INVENTOIL? A TToR/VE Y' are substantially free from aromatic Patented Mar. 11, 1947 l CATALYTIC IS OMERIZATON William R. Smith, Port Arthur, Tex., assignor to New York, N. Y., a corpo- The Texas Company,

ration of Delaware Application .January 11, 1.946, Serial No'. 640,584

This invention relates to the conversion of hydrocarbons. It has to do with the isomerization of hydrocarbons to form branched chain hydrocarbons. It is applicable particularly with respect to the isomerization of normal butane and saturated gasoline hydrocarbons.

The invention has to do with efiectingconversion of the hydrocarbons by the action of an active metallic halide catalyst in fluid form and in the presence of hydrogen halide wherein the hydrocarbons undergoing conversion are passed in dispersed phase through a body of the catalyst maintained in substantially continuous liquid phase.

This is a continuation-impart of my copending application Serial No. 448,728, led June 27," 1

In the copending application of John R. Callaway, Serial No. 488,811, filed May 28, 1943, which is a continuation-in-part of Serial No. 345,025, led July 12, a continuous process for isomerizing normal butane by dispersing the normal butane feed into the lower portion of a substantially static'column of liquid isomerization catalyst consisting essentially of aluminum chloride-hydrocarbon complex formed by reacting aluminum chloride with feed hydrocarbons consisting essentially of saturated C4 hydrocarbons in the presence of a small amount of hydrogen chloride at a temperature in the range about 160 to 240 F., the complex catalyst being substantially saturated with aluminum chloride but substantially free from suspended solid aluminum chloride, the dispersed normal butane feed rising in discontinuous phase upwardly through the column of liquid catalyst in continuous phase by differences in density in the presence ci a small amount of hydrogen chloride and at an elective isomerization temperature not exceeding about 240 F., whereby the dis- 9 Claims. (CL :M0-683.5)

. 2 while at the same time halide in solution in the effluent isomate stream discharging from the reaction tower is effectively avoided. In order ot maintain the desiredlevel of complex liquid within thefreaction tower, a small proportion of the complex liquid is- Withdrawn eithery continuously or intermittently; and to maintain the activity of' the complex liquid within the reaction' Zone over long periods of is added either continuously or 'intermittently 1940, there is disclosed and claimed" persed hydrocarbons are maintained in Contact with the catalyst for a period of time not in excess of about ten minutes so thata substantial conversion of normal butane to isobutane takes place in a single passage of feed hydrocarbons through the catalyst column. i

The present application relates .to thiscontinuous tower tyne of normal butane isomerization, and is'predicated on the discovery that by maintaining the complex liquid catalyst, formed by reacting a Friedel-Crafts metallic halide 'suchl as aluminum halide, with hydrocarbons v.which constituents, within a critical heat of hydrolysisfrange, effective conversion of the normal butane to isobutane in once-through operation is secured -from suspended solid aluminum halide. i

therefore, of such character that upon cencontinuous operation, additional metallic halide in an amount so regulated that the complex liquid `within the reaction Zone is kept within the aforementioned critical heat of hydrolysis range.

In accordance with the invention hydrocarbons undergoing conversion `are dispersed in line- 1y 'divided form, such as small droplets or particles and caused to rise in that form through a comparatively stationary or quiescent body of liquid catalyst maintained within a reaction zone, the volume of catalyst within the reaction zone being relatively large with respect to the volume 'of hydrocarbons passing through the catalyst body. The hydrocarbon reaction products are continuously withdrawn from the top of the reaction zone and provision may be made for the recycling of unconverted hydrocarbons tothe reaction.

The invention has particular application to the conversion of a low-boiling parai-n such as normal butane. In applying the invention Ato the isomerization of normal butane a particularly eilective catalyst consists essentially of a liquid complex compound .of aluminum halide and petroleum hydrocarbon which is substantially free It is,

trifuging at normal room temperature substantially no sediment or sludge is obtained.

It has been proposed heretofore to employ catalysts comprising solid aluminum halide or comprising mixtures of solid aluminum halide and complex compounds of aluminum halide and hydrocarbon. Thepresent invention, however,

4conten'xplates effecting isomerization of a saturated hydrocarbon'such as normal butane with a liquid catalyst consisting .essentially of metallic halide-hydrocarbon complex which is substantially free from undissolved solid aluminum halide.

liquid complex compound of aluminum chloride and hydrocarbon of such character that it has an apparent heat of hydrolysis within. the range from substantially above 200 calories per gram of complex to about 320 ycalories per gram of carryover of the metallic For example, an effective catalystv in vaccordance with this invention consists of a hydrocarbon complex.

' measurable heat not inexcess 'mal butane. is either gas or perature not in i o complex, equivalent to an absolute heat of hydrolysis from substantially above about 213 to about 341 calories per gram of complex; By apparent heat of hydrolysis is meant the calculated value ofthe heat liberated when a minor portion of the complex is mixed with a maior portion of water, the calculation being based upon the rise in temperature of the amount of Water used in the calorimeter. By absolute heat of hydrolysis is meant the calculated figureV obtained from the said apparent heat of hydrolysis by adding a certain percentage correction to compensate for the heat absorbed bythe calorimeter apparatus itself, as determined by a calibration of the calorimeter employed.

The heat liberated in this calorimeter test is the total of at least three principal effects: 1. The heat of hydrolysis of the aluminum chloride 2. The heat of solution in water of any .solid aluminum chloride present; and. 3. The heat obtained when aluminum chloride that is dissolvedin the complexA comes in contact with water and preferentially dissolves in the latter medium. Y

A complex prepared by treating 'an excess of aluminum halide with hydrocarbon Ysuch as kerosine and which is free from solids that would be separated by centrifuging the prepared complex at 3000 revolutions per minute for a half hour in an A. P. I. centrifuge at'about normal room an Vapparent cr of about 320 calcries per' grafo of complex upon mixing with water as described. Such a complex is particularlv suitable as a catalyst for isomerizing norliquid phase. When applying theV percentage correction for the amount of heat liberated which is absorbed bv the temperature. usually evolves calorimeter. then the absolute heat of hydrolysis of the' aforesaid complex calculates to about 341 cainries oer gram of complex.

The aluminum chloride content 'of a complex catalyst may vary considerably depending. for example. upon the hydrocarbons used in forming the complex. Irresnectivc of this. however,

the foregoing apparent heat value of about 300 t 320. with an absolute heat value of about 320 vto 341, seems to hold for a complex catalyst 'mixture saturated with aluminum chloride but free from solids which would appear as a sediment upon centrifuging as above described.

The presence of excess solid aluminum halide in the complex. such as is evidenced by the obsediment upon centrinormal butane because it apparently causes some cracking or other side reactions to occur, and results in aluminum halide carryover in the eiiluent isomate stream.

In 'practicingr the invention normal butane Vis subiected to contact with the liquid complex catalyst in the presence of hydrogen chloride at a temexcess of about 360 F. and prefsion is avoided. Liquid hydrocarbon feed may be erably at a temperature aboutrl() to 240,F. with a short period of contact.' Thistime Ici' contact may range from several seconds to several minutes or more depending upon the temperature maintained. By employing a complex catalyst having an apparent heat value of not more than 300 to 320 calories. equivalent to an absolute heat value of about 320 to 341 calories, a prolonged period of contact between butane and the catalyst can be maintainedv apparently without side reactions occurring at temperatures. in the' range up to as high as 215'to 220 F. l

- liquid phase through packing material ,for a certain portion of its -to simulate a saddle and known to the trade as #Berl saddles. It will be understood that such 4solid aluminum halide.

The feed hydrocarbon is passed in dispersed a comparatively stationary body v.of 'liquidcatalyst by difference in density `and the volume of liquid catalyst is maintained large relative to the volume of hydrocarbons undergoing conversion within the reaction zone. It appears that by maintaining the liquid catalyst in continuous phase and the hydrocarbons uny dergoing conversion in dispersedphase,A highly effective contact between hydrocarbon and catalyst is secured. Under these conditions the surface between feed hydrocarbon particles and the catalyst is continually distorted and broken down in a more effective manner, thereby insuring more ecient contact between hydrocarbon and catalyst. i

Notwithstanding the fact that under ordinary circumstances aluminum halide is soluble in bu tane to a substantial extent at the temperatures employed, it hasbeendiscovered that the liquid butane during passage through a complex catalyst of the above-described character apparently does not dissolve and extract aluminum halide'from the liquid catalyst body andy carry it out of the reaction zone. When liquefied normal butane flows through a Contact mass of;s olid aluminum halide, a substantial amount of the halide is dissolved in the butano and is removed as solute in the eiuent hydrocarbon. By contrast, when operating in accordance with the present invention employing a liquid catalyst as -already described the stream of hydrocarbon liquid leaving the reaction vzone is substantially free from aluminum'halide.

vMaintaining substantially unidirectional flow of the hydrocarbons undergoing conversion through the liquid catalyst body apparently facilitates the rapid removal of converted hydro- The operation is preferably carried out by passing the feed hydrocarbon in highly dispersed state upwardly through a -tower lled with the liquid catalystand. entirely free from agitation produced by a stirring-"mechanism so that subfstantial coalescence ofthe. hydrocarbon disperintroduced through a spray or jets placed in a Venturi section at the bottom of the tower. The tower may be either an unpacked tower free from obstructions, or it may contain a suitable inertV height, such as small contact pieces, each shaped a packing merely increases the length of the pathof flow of thel dispersed dropletslwithout causing substantial coalescence thereof.; and while reaction temperature of 210 maintaining the staticcondition of the column -level over prolonged periods of time, while carryover of aluminum halide in solution in the eiuent isomate stream is avoided.

In order to describe the method of practicing Y the invention, reference will now be made to the accompanying drawing.

As shown in the drawing a feed hydrocarbon consisting essentially of normal butane is drawn from a source 'not shown through a `pipe I and conducted to a heater 2 wherein the hydrocarbon is heated to a reaction temperature of about 210 F.

The heated hydrocarbon stream is passed from the heater through a pipe communicating with a spray discharge 4 located in the Venturi portion of a vertical reaction towerv 5. The sprays should discharge the feed particles without substantial impingement upon the sloping sides of the tower.

The reaction tower comprises a vertical vessel filled or substantially iilled with a large body of liquid complex catalyst to which reference will be made later.

Hydrogen chloride may be drawn from a source not shown through la pipe 6 communicating with a pipe 'l through which hydrogen chloride is introduced to the stream of heated feed hydrccarbon owing through the pipe 3. The amount of hydrogen chloride injected in the feed hydrocarbon stream may vary from a fraction of a per cent to 4 or 5 per cent but usually amounts to about 2 or 3 per cent 'by weight of the feed hydrocarbon introduced to the reaction zone.

The catalyst body within the reactor is maintained at the reaction temperature. The temperature may be maintained by adjusting the temperature of the entering feed and also by jacketing the tower. Since the reaction is slightlyexothermic it may of the heat of the reaction, although it is `coritemplated that the temperature may be allowed to rise so as to actually maintain a temperature gradient of 20 to 50 F. in the direction of hydrocarbon flow through the catalyst.

The volume of liquid catalyst maintained within the reactor and the rate of introduction of -feed hydrocarbons may be adjusted so as to maintain the volume of liquid catalyst in excess of that of the feed hydrocarbon within vthe reactor, and preferably in the proportion of about 2 to 100 volumes per volume of feed hydrocarbon within the reactor at any given instant.

Advantageously suiiicient pressure is maintained within the reactor 5 so that the feed hydrocarbon remains in the liquid phase. For

be necessary to extract some example, in the caser of normal butane the pressure may be about 335 to 350 pounds with a F. The feed hydrocarbon is dispersed in droplets by means of the discharge spray and the droplets or particles rise through the comparatively stationary body cf catalyst liquid by diiference in density.

The time of contact between the hydrocarbons and the catalyst may be altered by varying the ing undesired side reactions.

peratures favor realizing a concentration of isobutane reaction products.

It is Adesirable that the spray or sprays for introducing the feed to the bo-ttom of the reaction tower be so arranged and of such design as to introduce the feed hydrocarbon in a uniform dispersion of fine .droplets or particles extending .over the entire cross-sectionalarea of the tower, as disclosed and claimed in the copending application of Lynn R. Strawn, Serial No. 483.440, filed April 1'?, 1943, now Patent No. 2,389,651, dated November y2'?, 1945. The rate of feed introduction should be controlled so as to avoid displacement of liquid catalyst from the tower and also so as to avoid channelling of the hydrocarbons ilowing through the catalyst. It is desirable to have the hydrocarbons remain as discrete particles during passage through the liquid catalyst. Therefore, conditions should be controlled solas to avoid substantial coalescence of the individual particles during passage through the catalyst.

The reacted and unreacted hydrocarbons are continuously drawnr olf in a stream from the top of the reactor through -a pipe 8 through which they are conducted to a receiver or other vessel A9. The pressure may be released in part in the receiver 9 to permit gaseous constituents to escape through a pipe l0. Such gas may comprise mainly hydrogen chloride which is advantageously recycled, as indicated, to the reactor.

'The hydrocarbons are conducted from the receiver 9 through a pipe i2 to a fractionating unit i3 which may comprise one or more fractionating towersV so as to eifect any desired degree of fractionation of the hydrocarbon mixture.

For example, a gaseous fraction comprising hydrogen chloride may be removed and discharged through a pipe i4 for recycling to the reactor 5 or for such other disposition as may be desired. A. fraction comprising isobutane is drawn off through a pipe I5 while another stream comprising unreacted normal butane is drawn oi through a pipe l5. The unreacted normal butane mayA be recycled all or in part through a pipe l 'l to the previously-mentioned pipe I through which it is returned to the system for further conversion.

The preformed catalyst complex may be prepared by reacting aluminum halide with a petroleum hydrocarbon. or hydrocarbon mixture in the presence of hydrogen chloride. For example, 1000 parts by weight or^ anhydrous aluminum chloride powder is mixed with about 1630 parts by weight of kerosine derived from mixed base crude and having the following approximate characteristics:

A. P. I. gravity 43 Saybolt thermo-viscosity at 6.0 x 370 Initial boiling point i 34.7 20% point F 338 50% point 1 F-- 415 pongan F-- 47o End boiling point F-.. 490

i -"Iheforegoing mixture together with 50 parts by weight .of hydrogen chloride is charged to a closed reactor and agitated for about 4 hours `at a temperature of about 210 F. The reaction mixvture is thereafter cooled andthe moved and separated into phases. The complex phase is Vremoved fromthe hydrocarbon phase and this complex comprisesthe preformed liquid catalyst. Y

It is of such character that when a minor portion thereof is mixed with a major portion of water the heat evolved from Athe mixture is within the eiective isomerization activity range which avoids catalyst carryover by` solution in the effluent isomate stream as set' forth above. heat of the mixture-'is determined, for example, by breaking an ampoule'containing a weighed amount of complexgi. e.; about 3 grams in a weighed quantityof water, i. e., about 300 grams,

containedin a Thermos ask and initially at aboute' normal room temperature. The mixture is stirred and the rise in temperature me'asured'by means of a thermometer. VFrom thisthe apparent heat liberated is calculated 'as calories per gram of complex. Since the foregoing calculation is based upon the amount of water employed in the Thermos ilask or kcalorimeter used in the test, it is obvious that this apparent value does not include that portion of the heat liberated which is absorbed by the calorimeter itself. In"

order to make the test reproduciblefor diierent laboratories employing diierent calorimeters, the apparent heat of hydrolysis value as obtained above is converted to an absolute heat of hydrolysis value, so that any variation between dif ferent calorimeters is excluded from the absolute value reported. This is accomplished by calibrat- Y ing theparticular calorimeter used for determining the apparent heat of hydrolysis value. The

calibration is preferably accomplished by dilu-ting the same weight of water in the calorimeter, namely, about 300 grams, `with known weights of sulfuric acid, and calculating the waterequivalents of the system using the Bro-usted, Grau and Roth data for heat of dilution as reported by '-Bechowsky and Rossini in The Thermo Chemistry of the Chemical Substances, published by Reinhold, i936. .The difference between the known values, for theheat of dilution of the known weights of sulfuric acid employed and the values. calculated from the rise in temperature `vof the water used in the calorimeter represents the amount of heat absorbed by the calorimeter itself. From the fundamental formula 'WXAT s where W is the water equivalent of the system and equals the grams rof water placed in the apparatus plus water equivalent of the apparatus itself, AT is the temperature rise indegrees centigrade and S is grams of sample, itgis obvious 'that the correction to be applied to v,the-apparent heat of hydrolysis will vary directly in ac-A cordance with the heat liberated, and will therefore be a definite or iixed percentage of the apparent heat of hydrolysis value. A calibration of standard calorimeters employed in this work has shown that the percentage correction to be added to the apparent heat of hydrolysisvalue is approximately 6.6%. Consequently, the apparent heat of hydrolysis range from substantially above 200 to about 320 calories per gram of complex calculates to'an absolute'lheat of hydrolysis range contents re- Thef e isomerization activity level of vPer gram of complex, Y e Y Y heated stream of normal butane was introduced to the lower portion of a reaction tower, `15 feet in height, lled with liquidaluminum chloride-V kerosine complex prepared as describedv above.

In this instance the 'preformed complex was of such character that when a minorportion there,-k of was mixed with a` major portionof water the apparent heat liberated was about 300 calories per gram of complex, equivalent to an absolute heat of hydrolysis of 320.V The -rateof-normal butane charged to the tower and the volume of liquid complex within the tower vwas such that the volume ratioof liquid complex `to liquid 'buf tane within the tower was aboutlzl. Y Y

The stream of normal butane was passed through the complex catalyst for a period of about 430 hours, obtaining a total yield-of Aisobutane amounting to about 1351pounds per pound of aluminuml chloride actually contained inthe preformed complex. During this vperiod of operation the eiiiuent hydrocarbons contained 50 %iso butane, the remainder consisting essentially Vof unreacted normal butane. During prolonged continuous operation, some of the dissolved aluminum halide inthe complex liquid apparently reactswith the hydrocarbon, with the result that additional complex'liquid is T formed and the volume of complex liquid within the tower thus tends'to increase. ',At the same time, the heat of hydrolysis value ofthe Acatalyst tends to drop with a consequent reductionin the the catalyst.l AFor this reason means are provided for the withdrawal of a small "amount of catalyst mixture from the bottomof'the reaction tower-either intermittently or continuously to maintain the desired complex liquidi levelv within the tower,

and also for the controlled `additionof a small amount of aluminum halide to the catalyst body to maintain the activity of the catalyst withinV the effective conversion range. Such addition may be at intervals or continuously. For example such makeup ,aluminum halide may be dissolved in a small portion oiv the feed hydrocarbon and injected directly to the reaction tower. On the other hand a portion of the withdrawn catalyst mixture may have additional aluminum halide incorporated-therein and thereafter bereturned to the reactiontower. Y' In any case the amount of aluminum halide so added to the catalyst is adjusted so that the character of the catalyst body within the 'reaction tower will remain within thevcritical llimits of heat of hydrolysis as'previously d escribed. 1

While-mention has been madexof aluminum chloridev in preparing the complex, nevertheless it isicon'templated that other metallic halides including aluminum bromide, may be employed. It

is also contemplated that the reaction may be carried out Yin the'presence of hydrogen, hydrovvgen containing gases or other agents adapted to modify 'the reaction so desired. Likewise it is contemplated that temperature conditions, and

Ipressure conditions other thanv those specied above may be employed dependingy upon the nature of the hydrocarbon feedand the extent oi conversion desired. Y

In preparing the complex other petroleum hy drocarbons besides kerosine hydrocarbons may be used including gasoline hydrocarbons. Aliphatic hydrocarbons in general are preferred.

While mention has already been made of employing from 2 to 100 volumes of liquid catalyst per volume of hydrocarbon Within thev tower, nevertheless it is contemplated that substantially less than 2 volumes of catalyst may be employed. It is considered desirable when operating with the feed hydrocarbon maintained in the liquid phase to maintain conditions such that the hydrocarbon hold-up in the tower does not exceed a value in the range .about l to 75% by volume of the liquid catalyst.

It is desirable to avoid excessive holdup so as to keep the tower below the flooding point. Atl the flooding point the velocity of drop flow is substantially reduced and may be only about onehalf the velocity at just below this point.v As the flooding point is approached the rising dispersed phase droplets approach a condition of now characteristic of a close-packed drop column extending throughout the tower above the Venturisection.

A high drop velocity without drop coalescence` is desirable particularly with respect to obtaining a high conversion yield to isoparan without substantial occurrence of side reactions which might otherwise occur under the prevailing conditions of catalyst activity and reaction temperature. For example, a suitable drop velocity may range from about 0.1 to 0.2 or 0.5 feet per second'.

1t is also contemplated applying the invention to the treatment of other hydrocarbons besides normal butane. For example, other hydrocarbons may include pentane, hexane and the like. When isomerizing normal pentane a somewhat lower reaction temperature is desirable,y as for example, `a temperature of .about 150 F; Likewhen isomerizingafeed hydrocarbon. consisting essentially of normal hexane a still lower temperature such as about 100 F. is desirable. ln the casev of a hexane cut or fraction containnaphthene hydrocarbons substantially higher temperatures are usually required and in such ease the temperaure may be as high-as 250 F.

Provision may also be included for purifying fthe feed hydrocarbons prior to conversion. Such puriiicationmay involve the removal of olenic and aromatic constituent-skies well as water andsuiiur compounds or-other materialsv which tendl to poison or cause deterioration of the catalyst.

Obviously many modifications and variations of the invention as herei-nbefore set forth may be made without departingfrom the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

l. A continuous method ofV isomerizing saturated hydrocarbons which comprises maintaining within avertical reaction zone a substantially static column of. liquid catalyst consisting essentially of complex formed. by reacting a Friedel- Crafts metallic halide in the presence of hydrogen halide with hydrocarbonsv which are substantially free from aromatic constituents, continuously introducing saturated feedv hydrocarbon to the lower portion of said zone', passing the introduced hydrocarbons comprising C4 hydrocarbons .in dispersed liquid phase upwardly through the liquid column by difference in density in thepresence of a small amount of hydrogen halide atan. elevated temperature at least sulicient to effect substantial isomerization and not in excess of about 300 F., the height of said liquid catalyst column being such that substantial isomerization occurs in a single passage of feed hydrocarbonsv through the column, maintaining the volume of liquid catalyst in the column substantially greater than the volume of hydrocarbons undergoing treatmenttherein, maintaining the top of said catalyst column below the point of isomerized hydrocarbon discharge from the reaction zone, continuously removing from the top of said liquid catalyst col'- umn within the reaction zone a hydrocarbon phase containing isomerized hydrocarbons which is substantially free from dissolved metallic halide, introducing metallic halide to said catalyst column, and regulating the amount s'o introduced such that the complex is maintained at a predetermined level of activity and is character-l ized by having an absolute heat of hydrolysis in the range from substantially above 213 to about 341 calories per gram of complex.

2. The method according to claim l in which Ithe metallic halide is introduced as a solution in a stream of feed hydrocarbon entering the reaction zone.

3. A continuous method of isomerizing saturated hydrocarbons which comprises maintaining within a. vertical reaction zone a substantially static column of liquid catalyst consisting essentially of complexV formed by reacting aluminuml chloride in the presence of hydrogen halide with hydrocarbons which` are substantially free from aromatic constituents, continuously introducing feed hydrocarbonA to the lower portion of saidzone, passing the introduced hydrocarbons comprising Cihydrocarbons in dispersed liquidphase upwardly through the liquid column by difference in density in the presence of a small amount of hydrogen halide at an elevated temperature at least suflcient to-eilect substantial isomerizationand not in excess of about 300 F., the height of said liquid` catalyst column being such that substantial isomerization occurs in 'a single passage of feed hydrocarbons through the column, maintaining the volume of liquid catalyst in the column substantially greater than the volume of hydrocarbons undergoing treatment therein, maintaining thetop of said catalystcolumn below the point of isomerized hydrocarbon discharge from the reaction zone, continuously removing from the top of said liquid catalyst column within the reaction zione a, hydrocarbon phase containing isomerized hydrocarbons whichis substantially free from dissolvedaluminum chloride, introducing aluminum chloride to feed hydrocarbons passing. to said catalyst column, and regulating the amount so introduced' such that the complex is maintained at a predetermined level of activity and is characterized by having an absolute heat of hydrolysis substantially above 213 but not sub--y stantially greater than 341 calories vper gram of complexand being. substantially free from solids.

4.- A. continuous met odl of isomerizing normal butane which comprises maintaining within a verticalV reaction zone a` substantially static column of liquid catalyst consisting essentially of complex formed by reacting aluminum chloride in the presence of hydrogen chloride with hydrocarbons which are. substantially free from aromatic. constituents, continuously introducing normal butane to the. lower portion of said zone, passing the introduced. butane in dispersed liquid phase upwardly throughthe liquid column by difference in density in the presence of hydrogen chloride at a temperature in the range about 180 liquid catalyst in the column substantiallygreater than the volume of vhydrocarbons undergoing treatment therein, maintaining the top of catalyst column below the point of isobutane dis-i charge from the reaction zone; continuously removing from the top of said liquid catalyst column within the reaction zone a hydrocarbon phase containing isobutane which is substantially free from dissolved'aluminum chloride, introduc-v ing aluminum chloride to a stream of normal Vbu'- tane passing to the reaction zone, and regulating; the amount so introduced such that the complex is maintained at predetermined level of activity and is characterized by having an absolute heat of hydrolysis of about 320 to34l calories per gram of complex and is substantially free from solids;

5. A continuous method of isomerizingsaturated hydrocarbons which comprises maintaining Within a vertical reaction zone a substantially static column of liquid catalyst consistingessentially of complex formed by reacting aluminum halide in the presence of hydrogen halide with hydrocarbons aromatic constituents, continuously introducing feed hydrocarbon to the lower portion'of said zone, passing the introduced hydrocarbons comprising C4 hydrocarbons in dispersed liquid phase upwardly through the liquid column by diierence in density in the presence of hydrogen halide amounting to not in excess of about 5% by weight of feed hydrocarbonsand at an elevatedtemperature at least sufficient to -effectfsubstantial isomerization and not in excessfofabout 30W-F., the height of said liquid catalyst column being such that substantial isomerization occurs in a single passage of feed hydrocarbons through the column, maintaining the volume of liquid catalyst inthe column substantially greater than the volume of hydrocarbons undergoing treatment there'- in, continuously removingfrom the top of said liquid catalyst column within the reaction zone a hydrocarbon phase containing isomerized hydrocarbons which is substantially free from dissolved aluminum halide, introducing aluminum halide to maintaining the volume of- Which are substantially free from said catalyst column, and-regulating the amountv Y so introduced such that the complex is maine tained at a predetermined level of activity and is characterized by having an absolute-heat of hy` drolysis substantially'above-213 and not Vsubstantially exceeding about 341 calories ,per gram` of'complex.

' 6. A continuous method of isomerizing saturated hydrocarbons Which comprises disposing in a vertical reaction zone a substantially static column of liquid catalyst consisting essentially of complex formed by reacting aluminum halide in` the presence of hydrogen halide with aliphatic hydrocarbons substantially free from. aromatic constituents, said complex 'having al predetermined isomerizing activity and being characterized by having an absolute heat of hydrolysis'of about 320 to 341 calories per gram of complex and being substantially free -from solids, continuously introducing normal butane to the lovver portion of said zone, passing the introduced hydrocarbons in dispersed liquid 'phase vupwardly through the liquid column by difference in density in the presence of hydrogen halide amount"-v ing to Vnot in excess of about 5%vby Weight ofnor-V mal butane and at an elevated temperature ,atv

leastv sucient to effect substantial*isomerization 7. A continuous method for isomerizing `norl mal butane which comprises disposing Ain a vertical reaction zone a substantially static column oi' liquid catalyst consisting essentially of AlCl3 aliphatic hydrocarbon complex said complex having a predetermined isomerizing activity and being characterized by having an absolute heat of hydrolysis of rabout 320 vto 341 calories per gram of complex, continuously introducing normal butane to the lower portion of said zone,'passing the introduced butane in'dispersed liquidphase up- Wardly through the liquid column by difference in density inf the presence of hydrogen chloride amounting to not in excess of about 5%'by Weight of butane and atan elevated temperature at least sufiicient to effect substantialfisomerizaticn and not in excess of about 300F. the height of said liquid catalyst column being such that substantial isomerization occurs in aV single passage of butane through the column, continuously removing from the top of said liquid catalyst column Within the reaction zone a hydrocarbon phase containing isobutane and unreacted normal bu. tane, said hydrocarbon phase being substantially. free from dissolved aluminum ing said removed hydrocarbon phase into a fraction comprising essentially isobutane and a fraction comprising essentiallynormal butane, discharging said isobutane fraction,l recyclingsaid normal butanefraction at least in part as hydro-- carbon feedV tothe reaction zone,v introducing aluminum chloride to the catalyst column and regulating the amount of aluminum chloride so introduced such that the complex catalyst is maintained at substantially said predetermined activityand ofthe aforesaid character.

Y 8.A continuous. mcthod'for isomerizing nor'- mal butanerwhichcomprises passing a lstream othydrocarbons vcomprisingnormal butane in liquid phase `in contact withA a mass of liquid catalyst disposed- Within a reaction zone, catalyst consisting essentially of complex catalyst formed by reacting aluminum chloridewith-aliphatic hydrocarbons in the presence of Vhydrogen chloride at elevated temperature and having an absolute heat of hydrolysis in therange of substantially above 213 to about 341 calories per gram of complex at which thecatalyst hashigh isomerizing activity, effecting said .contact at a temperature in the range about 180 to 240 F. inthe presencev of .hydrogen chloride amounting to not in excess of about 5% by weight of feed hydrocarbons such that substantial isomerization occurs, continuously removing from the reaction zone a stream of hydrocarbon phase containing a substantial proportion of isobutane and relatively free from dissolved aluminum chloride,

Y and adding aluminum chloride in solution in a character: f

through the columnl conisomerized hydrocarbons halide, fractionatsaid 9. A continuous method for isomerizing normal about 5% drogen chloride amounting to not in excess of by Weight of normal butane and at a temperature in the range about 180 to 240 F. such that substantial isomerization occurs, continuously removing from the upper portion of said reaction zone a stream of hydrocarbon phase containing isomerized hydrocarbons relatively free from dissolved aluminum chloride, and adding aluminum chloride to the complex liquid at a controlled rate to maintain the said isomerization activity and the said absolute heat of hydrolysis range of the liquid catalyst.

WILLIAM R. SMITH. 

